Computational Analysis to Evaluate the Effects of Knee Brace on Anterior Cruciate Ligament during Single-Leg Jump Landing

Abstract

Injury and musculoskeletal diseases in the knee due to excessive loading at the ligaments can cause mechanical instability to the joint. Knee bracing has been commonly used to support and provide external stabilization to the joint by restraining its motion and redistributing loads acting on the ligaments. Several studies have been conducted to quantify the effectiveness of knee braces in ligament injury prevention during static and quasi-static loading conditions. However, studies to assess them in dynamic loading conditions remain limited.

The aim of this study was to determine the effects of the mechanical design of the Stoko K1 knee brace on the strain behaviour of the Anterior Cruciate Ligament (ACL) in dynamic loading conditions computationally using Finite Element (FE) analysis. The Stoko knee brace evaluated in the current study utilizes a compliant design that has a system of non-extensible pre- tensioned cables running through a compression tight along designed pathways to stabilize the knee mechanics. An FE model of the knee brace was developed on an existing FE model of a knee. The FE model was validated in quasi-static varus/valgus loading conditions by comparing the effective load reduction at the knee to experimental test data available. Single-leg jump landing simulations were then conducted in braced configuration by inputting the muscle forces and joint kinematic/kinetic profiles for ten participants. ACL strain behaviours for post-ground contact duration of 200ms were compared between braced and unbraced configurations to assess the efficacy of knee brace in reducing ligament injury.

The results showed that the effective load at the knee reduced with the brace compared to without the brace during quasi-static varus/valgus loading, similar to the experimental results. Load reduction in braced configuration compared to unbraced configuration was 4.15% during valgus and 29.3% during varus loading condition. During the jump-landing activity, the mean ACL strain in braced configuration increased to 6.59 ±2.41% from 5.54 ±2.41% (p = 0.024) in unbraced configuration. The mean time taken for ACL to peak decreased from 80.66 ±27.14 ms in unbraced configuration to 61.33 ±24.61 ms (p = 0.007) in braced configuration. It was concluded that the mechanical design of the knee brace could cause the ACL strain to increase during dynamic loading. However, further studies are necessary to evaluate the changes in muscle firing patterns in the braced configuration, their effect on ACL strain behaviour and the effect of knee brace on other knee ligaments such as the Medial Collateral Ligament and Lateral Collateral Ligament.